my greed dice-game solution for ruby koans (http://rubykoans.com/)

greed-dice-game.rb

require File.expand_path(File.dirname(__FILE__) + '/neo')

# Greed is a dice game where you roll up to five dice to accumulate
# points.  The following "score" function will be used to calculate the
# score of a single roll of the dice.
#
# A greed roll is scored as follows:
#
# * A set of three ones is 1000 points
#
# * A set of three numbers (other than ones) is worth 100 times the
#   number. (e.g. three fives is 500 points).
#
# * A one (that is not part of a set of three) is worth 100 points.
#
# * A five (that is not part of a set of three) is worth 50 points.
#
# * Everything else is worth 0 points.
#
#
# Examples:
#
# score([1,1,1,5,1]) => 1150 points
# score([2,3,4,6,2]) => 0 points
# score([3,4,5,3,3]) => 350 points
# score([1,5,1,2,4]) => 250 points
#
# More scoring examples are given in the tests below:
#
# Your goal is to write the score method.

def score(dice)
  def calc_three_set (dice, num, val)
    # replace 3 occurrences of num with val
    count = dice.count num
    return dice if count < 3 # no three set
    
    dice.delete num # delete all occurrences of num
    # refill if there are more than 3 num
    count -= 3; count.times { dice << num }
    dice << val
  end

  def calc_individual_dice (num)
    return num if num >= 100 # val from three sets
    return 100 if num == 1
    return 50 if num == 5
    return 0
  end
                      
  # check if there is any three set
  calc_three_set dice, 1, 1000
  (2..6).each {|x| calc_three_set dice, x, 100*x }

  dice << 0 # return 0 if dice.empty?
  return dice.collect {|x| calc_individual_dice x }.reduce :+
  
end

class AboutScoringProject < Neo::Koan
  def test_score_of_an_empty_list_is_zero
    assert_equal 0, score([])
  end

  def test_score_of_a_single_roll_of_5_is_50
    assert_equal 50, score([5])
  end

  def test_score_of_a_single_roll_of_1_is_100
    assert_equal 100, score([1])
  end

  def test_score_of_multiple_1s_and_5s_is_the_sum_of_individual_scores
    assert_equal 300, score([1,5,5,1])
  end

  def test_score_of_single_2s_3s_4s_and_6s_are_zero
    assert_equal 0, score([2,3,4,6])
  end

  def test_score_of_a_triple_1_is_1000
    assert_equal 1000, score([1,1,1])
  end

  def test_score_of_other_triples_is_100x
    assert_equal 200, score([2,2,2])
    assert_equal 300, score([3,3,3])
    assert_equal 400, score([4,4,4])
    assert_equal 500, score([5,5,5])
    assert_equal 600, score([6,6,6])
  end

  def test_score_of_mixed_is_sum
    assert_equal 250, score([2,5,2,2,3])
    assert_equal 550, score([5,5,5,5])
    assert_equal 1100, score([1,1,1,1])
    assert_equal 1200, score([1,1,1,1,1])
    assert_equal 1150, score([1,1,1,5,1])
  end

end

\m/ . It seems great but it's beyond my knowledge. You are using assert_equal which is very unfamiliar to me because, shamefully, I never wrote a test before in my life. :D